openapi: 3.0.3
info: { title: Discount API, version: 1.0.0 }
servers: [ { url: https://your-domain.com/api/v1 } ]
tags: [ { name: Discounts } ]
security: [ { bearerAuth: [] } ]

paths:
  /discounts:
    get:
      tags: [Discounts]
      summary: List discount vouchers
      parameters:
        - in: query
          name: active
          schema: { type: boolean }
      responses:
        "200": { description: Discount vouchers }

  /discounts/code/{code}:
    get:
      tags: [Discounts]
      summary: Get discount by code
      parameters:
        - in: path
          name: code
          required: true
          schema: { type: string }
      responses:
        "200": { description: Discount voucher }
        "404": { description: Not found }

  /discounts/apply:
    post:
      tags: [Discounts]
      summary: Apply a discount voucher to an invoice
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required: [code, invoice_id]
              properties:
                code: { type: string }
                invoice_id: { type: integer }
      responses:
        "200": { description: Discount applied }